VIVA: Physiology - Renal

Question 1

What are the physiological consequences of impaired renal function?

Answer 1

3/4 to pass:
1. Proteinuria*:
- Predominantly albuminuria
- Due to increased permeability of glomerular capillaries

2. Uraemia:
   - Accumulation of breakdown products of protein metabolism resulting in symptoms of uraemia
3. Acidosis:
   - Failure to excrete acid products of digestion/metabolism with urine maximally acidified
   - Total amount of H+ secreted reduced due to impaired renal tubular production of NH4+
   - Exception: renal tubular acidosis (impaired ability to acidify urine)
   - Hyperkalaemia due to H+/K+ exchange
4. Abnormal Na+ handling (retains excess amounts Na+), due to three mechanisms:
   - Acute glomerulonephritis: amount of Na+ filtered markedly decreased
   - Nephrotic syndrome: increased aldosterone causes salt retention, low plasma proteins means fluctuating shifts from plasma into interstitium, resulting low plasma volume triggers RAAS
   - Volume overload